This invention relates to mould tools, in particular to mould tools for moulding parts to a desired specification.
Moulding is a well known process that involves shaping a material when in a flowable or semi flowable form. There are many factors that effect the properties on a moulded part, for example the orientation of any filler therein and the degree of crystallinity and/or cross linking of polymer molecules (when moulding plastics). In many cases, providing a certain degree of strength is required then any actual variance between parts is overlooked providing they all fall within a rough tolerance band.
With the movement of polymer parts into more critical industries it is becoming ever increasingly important to be certain that a moulded part has the desired properties. For example it is critical that large polymer panels used in fuselage sections of aircraft have the desired structural strength and impact resistance.
Currently such safety critical parts are manufactured in autoclaves which are essentially large ovens which have a very closely controlled temperature. The parts are then processed through a moulding process in which the temperature of the mould is closely controlled. One drawback of this approach is the thermal mass of autoclaves as the entire moulds are normally placed within them. This means that, for the temperature to be controlled any changes in temperature can only occur very slowly. This eliminates the possibility of for example crash cooling a moulded part once the required crystallinity has been reached.
A further problem with the autoclave approach is that as the whole mould is located in the autoclave it is very difficult to control the heat input into different areas of a work piece being moulded at different rates. To this end the design of parts is largely a black art that often involves many design iterations and moulding parameter iterations before repeatable parts are produced to specification.